The present invention relates generally to a scroll expresser for use in a refrigeration system.
Scroll compressors are utilized in many refrigerant systems. After compression of a refrigerant in the scroll compressor to a high pressure, the refrigerant is cooled in a condenser and expanded to a low pressure in an expansion device. After heating of the refrigerant in an evaporator, the refrigerant again enters the scroll compressor, completing the cycle.
Scroll compressors include two opposed interfitting scroll plates each having a base and a generally spiral wrap extending from the base. The opposed scroll members define compression chambers. One of the two scroll members is driven to orbit relative to the other by a shaft. As the wraps orbit, refrigerant in the compression chambers are reduced in volume, increasing the pressure of the refrigerant.
It is desirable to increase efficiency of a refrigeration system. In all phase changing refrigeration systems, energy is lost at the expansion valve. It would be desirable to employ a refrigeration system with a device in place of an expansion valve which utilizes or recovers the energy of the expansion process in a more efficient manner.
The refrigerant system of the present invention employs a scroll expressor in place of an expansion valve. A non-orbiting expander scroll plate and an orbiting expander scroll plate form a plurality of expansion chambers. A non-orbiting compressor scroll plate and an orbiting compressor scroll plate form a plurality of compression chambers. The orbiting compressor scroll plate is keyed to the orbiting expander scroll plate such that the orbiting scroll plates move in the same direction and at the same speed. The orbiting scroll plates move by an off-center crank piece. As the center of mass of the crank piece and the orbiting scroll is not centered, a counter weight is employed to balance the radial inertial force due to the uncentered mass and prevent radial loading.
Refrigerant enters the expansion chambers through a high pressure refrigerant inlet. In the expansion chambers, the high pressure refrigerant is expanded to a mixture of low pressure vapor refrigerant and liquid refrigerant. The expanded liquid refrigerant exits the scroll expresser through a low pressure discharge. The low pressure vapor refrigerant flows into the compression chambers for compression. Any excess vapor not ingested by the compressor exits the expressor through the low pressure discharge. A separation element prevents passage of the liquid refrigerant into the compression chambers. After compression of the vapor refrigerant in the compression chambers, the refrigerant is discharged through a high pressure vapor discharge and mixes with refrigerant exiting the system compressor which is connected to the scroll expressor in parallel. Preferably, the volume ratio of the expansion chambers is greater than the volume ratio of the compression chambers.
A spring positioned between the orbiting expander scroll plate and the orbiting compressor scroll plate reduces both axial loading and axial clearance in the scroll expresser. The spring counteracts the tendency of the high pressure gases in the compression chambers to separate the orbiting compressor scroll plate from the non-orbiting compressor scroll plate. The spring also counteracts any gaps which may form due to wearing of the scroll plates and cause leakage.
Alternatively, the orbiting scroll plates may be integrated into one component. A drive mechanism with a combined crank piece and counterweight guides the orbiting scroll plate to cause expansion and compression of the refrigerant.
These and other features of the present invention will be best understood from the following specification and drawings.